<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    div.window {
        position: absolute;
        width: 300px;
        height: 200px;
        border: 3px outset gray;
    }

    div.titlebar {
        position: absolute;
        top: 0px;
        height: 18px;
        width: 290px;
        background-color: #aaa;
        border-bottom: groove gray 2px;
    }

    div.content {
        position: absolute;
        top: 25px;
        height: 165px;
        width: 290px;
        padding: 5px;
        overflow: auth;
        background-color: #fff;
    }
</style>

<body>
    <div class="window" style="left: 10px;top: 10px; z-index:10;">
        <div class="titlebar">Another window</div>
        <div class="content">
            <br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br>
            <br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br>
            <br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br>
            <br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br>
        </div>
    </div>

    <div class="window" style="left: 75px;top: 110px; z-index:20;">
        <div class="titlebar">Another window</div>
        <div class="content translucent"
            style="backround-color: #ccc; font-weight:bold;">
           This is another window. Its <tt>z-index</tt> puts it on top of the other one.
        </div>
    </div>

</body>

</html>